1. Field of the Invention
The present invention relates to a projector-type vehicle headlamp, and in particular to a vehicle headlamp having a movable shade.
2. Related Art
There is a projector-type vehicle headlamp having a projection lens arranged on an optical axis extending in a longitudinal direction of a vehicle and a light source arranged behind a rear focus of a projection lens. The projector-type vehicle headlamp is designed to reflect light from the light source onto an area close to the optical axis. When a low beam light distribution pattern is formed, a shade arranged so as to position its top end edge near the optical axis in a vicinity of the rear focus of the projection lens is used to shield a part of a reflected light from a reflector to form a predetermined cutoff line at a top end of a low beam light distribution pattern.
Disclosed in JP-A-2003-257218 is a projector-type vehicle headlamp having a movable shade designed to move between a light shielding position where a top end edge of a shade is positioned near an optical axis in a vicinity of a rear focus of a projection lens and a light shielding alleviating position where a shading amount for reflected light from a reflector is reduced than the light shielding position.
The vehicle headlamp described in JP-A-2003-257218 can form a high beam light distribution pattern by moving the movable shade to the light shielding alleviating position. Therefore, a single lighting fixture unit can be used for a low beam and a high beam.
According to the project-type vehicle headlamp, when a low beam light distribution pattern is formed, a crisp cutoff line can be formed at a top end of the low beam light distribution pattern. However, this provides a light distribution pattern that has a high intensity up to a neighborhood of the cutoff line. As a result, when the vehicle is pitching, a glare is caused to the drivers of oncoming vehicles.